Sliver drawing rollers driven by belts including belt cleaners

ABSTRACT

Drawing frame for drawing fiber sliver with draw frame rollers comprising a pair of pre-drawing rollers and a main drawing roller pair. Power transmission members in the form of flat belts are used for driving the draw frame rollers. A deflection pulley engages the flat belts between respective pairs of wheels deflecting the belts for increasing the angle that the flat belt extends around the respective wheels to provide a non-slip engagement between the flat belts and the respective wheels.

BACKGROUND OF THE INVENTION

1. Field of Invention

The instant invention relates to a drawing frame to draw fiber sliverswith drawing rollers constituting pre-drawing and main drawing rollerpairs and power transmission means to drive said drawing rollers as wellas a sliver discharge mechanism.

2. Background of Art

The utilization of drawing rollers with two or more pairs of rollers todraw fiber slivers is known. The circumferential speed of the pairs ofrollers increases from the inlet of the drawing frame to the outlet ofthe drawing frame. The lower roller of the roller pairs is driven bytoothed wheels or toothed belts so to produce the slippage-freeoperation which is absolutely necessary for orderly drawing of the fiberslivers. The upper rollers are pressed against the lower rollers and therollers thus clamp the fiber material running through between them.

It has been shown that toothed-wheel drives as well as toothed-beltdrives of the drawing frame rollers have a detrimental effect upon theuniformity of fiber sliver drawing.

With toothed-wheel drives the clearance which exists between theindividual teeth of the toothed wheels causes the roller pairs not to bedriven simultaneously but one after the other, especially during run-upof the drawing-frame. This produces irregularities in the drawing of thefiber sliver.

DE-OS 20 44 996 proposes driving the drawing rollers via toothed belts.When such drives are used it was found that the accumulation of dirtbetween the teeth of the drive and deflection wheels over which thetoothed belts are guided, as well as between the teeth of the toothedbelt, cause irregular rotational movements of the drawing frame rollersto be produced. These irregularities lead to interference in the drawingof the fiber sliver as well as to increased wear of the drive elements.Especially where small toothed wheels are used and with toothed beltswith small tooth divisions, such as are required for predrawing rollersbecause of the limited space available, soiling of the tooth clearanceshas a very detrimental effect. Manual cleaning of drive and deflectionwheels as well as of the toothed belts is time consuming.

In addition to dirt, the oscillating characteristics of the drive meansat the constantly increasing drawing speeds seriously impair theuniformity of fiber sliver drawing. Toothed-belt drives have unfavorableoscillating characteristics at high predrawing speeds.

SUMMARY OF THE INVENTION

It is the object of the instant invention to create a substantiallymaintenance-free drawing-frame roller drive without slippage between thedrive element and the drawing-frame roller, making it possible to drivethe drawing-frame rollers in an orderly, uniform and rapid manner.

This object is attained through the instant invention in that powertransmission means are used to drive the drawing-frame rollers, wherebyat least one of these power-transmission means is a flat belt wrappingaround the driving wheels, with the loop of the flat belt wrappingaround at least one of the driving wheels being increased by theinstallation of deflection pulleys. Flat belts surprisingly make iteminently possible to achieve high speeds of the drawing-frame rollersat delivery speeds of over 500m/min. Their utilization aspower-transmission means to drive drawing-frame rollers has apparentlyfailed until now because it did not appear possible to ensureslippage-free transmission of the drive forces in this manner. Byinstalling deflection wheels to increase the angle of wrap of the flatbelt around the driving wheels of the drawing-frame rollers it has beenpossible for the first time to achieve slippage-free and therebyprecisely adjustable rotational speeds of drawing-frame rollers in thefield of roller drawing frames. By providing deflection wheels, the wrapof the flat belt around the driving wheels is increased to such anextent that the power transmission makes it possible to achieveslippage-free and therefore precisely adjustable rotational speeds ofdrawing-frame rollers. By providing deflection wheels, the wrap of theflat belts around the driving wheels is increased to such an extent thatthe power transmission from drive motor to the drawing-frame rollers isslippage-free. A further advantage is achieved by applying deflection ordriving wheels to the flat belts on both sides, one after the other. Inthis manner the flat belt is bent from the left side as well as from theright side per revolution. This varied bending of the flat belt ensurescleaning and thereby constant transmissible power.

The pre-drawing rollers are advantageously connected to each other bymeans of a flat belt for driving. This results in precise assignment ofthe speed conditions of the pre-drawing roller pair. If at least onedeflection pulley is installed in the direction of belt movement betweenthe driving wheels of the pre-drawing rollers, the flat belt extendingaround the deflection pulley and the driving wheels is bent alternatelyas it revolves and the wrap is thus increased.

An angle of wrap of at least 180° between flat belt and driving wheel ofthe lower drawing-frame roller has proven to be advantageous. With thiswrap an essentially slippage-free drive of the pre-drawing rollers wasobtained. If the flat belt is led over a deflection pulley installed ona tensioning lever provided with a spring element to produce therequired belt tension, uniform running of the drawing-frame rollers isadvantageously ensured.

Where flat belts are used in a very dusty environment, it isadvantageous to install cleaning devices. These cleaning devices actupon the contact surfaces of the driving wheels, the deflection pulleysand of the running surfaces of the flat belts. This prevents impuritiesfrom being ground into the flat belt, the disks and the rollers, leadingto unfavorable changes of the friction parameters that would causeslippage. This would lead to unwanted changes in the multiplicationconditions of the drawing-frame rollers.

In order to change the draft of the fiber sliver it is advantageous forat least one of the driving wheels installed on the drawing-free rollersto be capable of being replaced. By using driving wheels with differentdiameters, changes in gear multiplication conditions are easilyachieved.

In an advantageous further development of the device the flat belt istaken over a deflection pulley rotatably mounted on a free end of atensioning lever capable of being swiveled around an axis. Thetensioning lever is connected by means of a spring to a stationaryhousing part in such manner that the tensioning roller exerts atensioning force upon the flat belt. The path of the spring isadvantageously sufficiently great so that when different driving wheeldiameters are used, the flat belt can still be brought to its desiredtension. This desired tension can be set by means of a clamp screwprovided on the tensioning lever.

Rubber has proven to be an advantageous material for the flat belts.Flat belts made of rubber achieve good results from the point of view ofstretchability, slippage in combination with steel driving wheels andoscillation behavior. If the flat belts are provided with tractionelements made of polyamide, good results are achieved in the draftuniformity of the fiber sliver.

If the flat belts are provided with aramide traction elements, theresults can be further improved with respect to the oscillating behaviorof the flat belt.

When flat belts are used where at least the surfaces coming into contactwith the driving wheels are structured, high frictional values areobtained, contributing to slippage-free drive of the drawing-framerollers.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention is explained through the figures in which

FIG. 1 shows a section of the gear plan of a drawing frame

FIG. 2 shows a pre-drawing drive and

FIG. 3 shows a main drawing drive.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The section of a gear plan of a drawing frame shown in FIG. 1 shows theconnections between motor 1 and drawing-frame rollers 30, 31, 32. Thelower drawing-frame rollers in particular are driven by means of flatbelts. The rotation of the upper drawing-frame rollers is obtained bypressing the upper rollers against the lower rollers.

The driving wheels 2 driven by motor 1 are connected by means of a flatbelt 20 and driving wheels 3 to a main drive shaft 40. The drivingwheels 2 and 3 are made in the form of step rollers so that differentgear multiplications can be achieved by wrapping the flat belt 20therearound.

The rotations of the drawing-frame rollers 30, 31, 32 are adjusted fromthe main drive shaft 40 via driving wheels 4 and 10. The driving wheel 4is connected for driving by means of a belt 22 and a driving wheel 5 toan intermediate drive shaft 41. The drawing-frame roller 30 is driven bythe intermediate drive shaft 41 via driving wheels 6 and 7 which areconnected to each other by a belt 23. Thanks to the arrangement of thedriving wheels 4, 5, 6 and 7 which have different diameters, a suitablerotational movement can be transmitted to the drawing-frame roller 30 ata function of the fiber sliver to be drawn as well as of the draft to beimparted to the fiber sliver. By exchanging the wheels 4, 5, 6 or 7,changes in the rotational speed of the drawing-frame roller 30 can beachieved. Toothed belts 22 and 23 are preferably used for this drive inthe draft modification gear system that includes the wheels 4, 5, 6 and7. The degree of draft can be varied by changing the arrangement of thedifferent diameter wheels 4, 5, 6 and 7.

The drawing-frame rollers 30, 31 effecting a pre-drawing of the fibersliver are connected for drive by means of a flat belt 24. Through anappropriate selection of the diameter of the driving wheels 8 and 9 itis possible to achieve a rotational speed ratio between thedrawing-frame rollers 30 and 31 that determines the extent ofpre-drawing of the fiber sliver. Driving wheels 8 and 9 with a diameteressentially between 20 and 40 mm have been shown to be advantageous. Foran adaptation to different fiber material to be drawn, the distancebetween drawing-frame rollers, in particular between the pre-drawingroller 30 and 31, can be changed.

A rotational movement serving to drive the calendar rollers 422 via adriving wheel 11 on an intermediary drive shaft 42 to drive therotational tray 437 and the can tray 46 is selected from the main driveshaft 40 by means of the driving wheel 10 and a flat belt 21. The flatbelt 21 furthermore selects the rotational movement of the drawing-frameroller 32 by means of a driving wheel 12. The drawing-frame roller 32effects the main draft of the fiber sliver.

The fiber sliver delivered by the drawing-frame roller 32 and going intoa running direction A is brought by the calendar rollers 442 into thedischarge pipe 438 of the discharge wheel 437 and is discharged fromthis rotating discharge pipe 438 into a rotatable can 47. The calendarrollers 442 are driven via intermediary drive shaft 42 and a drivingwheel 44 is driven via a flat belt 441. The rotating tray 437 is drivenvia a driving wheel 43 mounted on the intermediary drive shaft 42 bymeans of a flat belt 431 which drives the driving wheel 434 viadeflection pulleys 432 in form of an V-drive, said driving wheel 434,being fixedly connected to driving wheel 43, driving the rotating tray437 via flat belt 436. The utilization of a flat belt installed in formof a V-drive is much less expensive and more reliable in operation thena bevel-gear drive which can also be used. The can tray 46 is driven bymeans of drive 45 via driving wheel 434 to impart a rotational movementto the can 47 selectively during the filling process. This advantageousarrangement makes it possible to carry out an absolutely jolt-freedepositing of the fiber sliver into the can and thereby also to ensureproblem-free presentation at further processing machines.

FIG. 2 shows the drive of the pre-drawing rollers. The driving wheels 8and 9 are connected to each other for drive by means of the flat belt24. A deflection pulley 13 is installed between the driving wheel 8 andthe driving wheel 9. The deflection pulley 13 advantageously causes thedriving wheels 8 and 9 to be contacted by the flat belt 24 over a largearea of their circumferential surface. The driving disk 8 is surroundedby the flat belt 24 with an angle of wrap of over 180°. This alsoapplies to the driving wheel 9. This driving wheel 9 is also surroundedby the flat belt 24 with an angle of wrap that is also greater than 180°. As a result the frictional force between the flat belt 24 and thedriving wheels 8 or 9 is sufficiently great so that slippage-freedriving of the drawing-frame rollers 30 and 31 connected to the drivingdisks 8 and 9 can be achieved. Rubber has proven to be an advantageousfrictional partner for the flat belt 24 and steel for the driving wheels8 or 9. Especially synthetic rubber, e.g. acrylonitrile butadien rubberwith a structured surface yields good frictional values of

0.7. If the flat belts are provided with polyamide traction elements,the flat belts can be stretched to such an extent that the belt tensioncapable of being produced yields very quiet running and thus gooddrawing results.

The deflection pulley 13 is advantageously stationary and placed in sucha manner between the driving wheels 8 and 9 that an angle of wrap ofover 180° is ensured independently of the size of the driving wheels 8and 9. In order to process different fiber materials, the distancesbetween drawing-frame rollers are modified. In order to avoid a decreaseof the angle of wrap to less than 180° for instance, at least twoattachment points are provided for the deflection pulley 13 at whichsaid deflection pulley 13 is held between the driving wheels 8 and 9 ina stationary manner.

To equal advantage, the deflection pulley 13 is installed in such mannerthat the tensioning roller and the deflection pulley are on the sameside of the plane in which the axes of the predrawing drawing rollerslie. This plane divides the space into two areas, with the tensioningroller and the deflection pulley being both in one of these areas.

If flat polyamide belts are used the advantage is gained that this typeof belt cannot be over-stretched in practice. Easy assembly of the flatbelts is thereby possible. In case of highly precise drawing of thefiber sliver, or when extremely high drawing speeds are used, theutilization of flat belts provided with aramide traction bodies hasproven advantageous. Such flat belts have an even better oscillating andstretching behavior than the polyamide belt, so that oscillations androtational speeds of the drawing-frame rollers can be further reduced.

The tensioning of the flat belt 24 is effected by means of a deflectionpulley 14 mounted on a tensioning lever 50. The tensioning lever 50 ismounted rotatably over a rotational axis 51. A spring 53 producespre-tensioning of the flat belt 24 to a predetermined bearing tension.The deflection pulley 14 is fixed in its position by means of anadjusting screw 52. The path of the spring 53 is sufficiently long so asto compensate for the utilization of driving wheels 8 and 9 withdifferent diameters producing a change in position of the deflectionpulley 14 while the length of the flat belt 24 is maintained. A handle54 is provided on the tensioning lever 50 in order to release thetension of the flat belt 24. The pre-tension of the belt 24 is reducedby loosening the adjusting screw 52 and by turning the handle 54 againstthe spring force in order to replace the flat belt 24 or to change thesize or position of the driving wheels 8, 9. By fixing the tensioninglever 50 in this position by means of the adjusting screw 52, rapid andeasy replacement of the flat belt 24 is made possible.

If different flat belts 24 are used, springs with different springforces are used in function of the desired belt tension, these springforces being adapted to these belt tensions. It may also be advantageousto provide several points of attachment of the spring 52 on thetensioning lever 50 so that the spring force may be varied by usingdifferent lever arms.

Wheel cleaners 60 are provided on the driving wheels 8 and 9 as well ason the deflection pulley 13 and on the tensioning roller 14. These diskcleaners 60 cause stripping of the contact surfaces between the disksand the flat belt 24. Accumulation of dirt on the disks, leading tofaulty drawing of the fiber sliver is thus avoided. Such drawing faultsare due on the one hand to the fact that dirt causes accelerations anddecelerations of the driving wheels and on the other hand to the factthat changes in the friction coefficient provoke slippage between flatbelt 24 and driving wheels 8 and 9. In a particularly dusty environmentit is advantageous to bring such cleaning elements also into engagementwith the contact surfaces on the flat belt 24. Band strippers 61 shouldbe placed so that they strip off the flat belt 24 before contact withthe driving disks 8 and 9. Cleaning devices of this type can of coursealso be used with the other flat-belt drives of the drawing frame.

Stripping brushes which are in contact with the disks, rolls and flatbelt are most suitable cleaning devices.

FIG. 3 shows the drive of drawing-frame roller 32 which serves to effectthe main drawing action. The rotational movement is transmitted from thedrive shaft 40 via a driving wheel 10 to the flat belt 21. In theembodiment of FIG. 3 the driving wheel 12 of the drive of thedrawing-frame roller 32 on the one hand, and the driving wheel 11 of thedrive of the intermediate driving shaft 42 on the other hand is moved bymeans of the flat belt 21. Two deflection pulleys 15 and 16 are providedafter the driving wheel 11, in direction P of belt movement. Thesedeflection pulleys 15, 16 cause the driving wheel 10 to be surrounded byflat belt 21 at a large angle of wrap. This ensures that the rotationalmovement of the main drive shaft 40 is transmitted without slippage tothe flat belt 21. In the embodiment of FIG. 3 the driving wheel 11 ofthe intermediate drive shaft 42 serves as a deflection pulley toincrease the angle of wrap of the flat belt 21 around the driving wheel12, thus ensuring slippage-free driving of the drawing-frame roller 32.

By using high-faced driving wheels disks and deflection pulleys, goodlateral guidance of the belts is ensured.

The instant invention is not limited to the embodiment shown here.Drawing frames according to the instant invention can be used whereverfiber slivers or roves are to be drawn at particularly high speeds. Thisnot only applies to the drawing frames described here, but also todrawing frames of spinning machines, for example.

I claim:
 1. Drawing frame for drawing fiber sliver with drawing framerollers comprising a pair of pre-drawing rollers, and a pair of maindrawing rollers, each of said rollers being fixed to a respective shaft,a wheel for driving each of said shafts being fixed adjacent an end ofeach respective shaft, power transmission means engaging said wheels fordriving said draw frame roller's wherein at least one of said powertransmission means is a flat belt surrounding a respective pair of saidwheels, a deflection pulley engaging and deflecting said flat beltbetween said respective pair of said wheels, said deflection increasingan angle that form as said flat belt wraps around said respective wheelsfor providing a non-slip engagement between said flat belt and saidrespective wheels and cleaning devices in contact with said flat belt.2. The drawing frame as set forth in claim 1 further comprising:cleaningdevices in contact with at least some of said wheels.
 3. The drawingframe as set forth in claim 2 wherein said cleaning devices arestripping brushes.
 4. The drawing frame as set forth in claim 1 furthercomprising:a can for receiving said drawn slivers, a rotational traycarried on top of said can for guiding said drawn sliver into said can,a second flat belt means for driving said rotational tray.
 5. The drawframe as set forth in claim 1 wherein said cleaning devices includes asecond deflection pulley carried adjacent said first mentioneddeflection pulley on an opposite side of said flat belt for deflectingsaid belt in an opposite direction from which said first mentionedpulley is deflecting said belt.
 6. Drawing frame for drawing fibersliver with drawing frame rollers comprising a pair of pre-drawingrollers, and a pair of main drawing rollers, each of said rollers beingfixed to a respective shaft, a wheel for driving each of said shaftsbeing fixed adjacent an end of each respective shaft, power transmissionmeans engaging said wheels for driving said draw frame roller's, whereinat least one of said power transmission means is a flat belt surroundinga respective pair of said wheels, a deflection pulley engaging anddeflecting said flat belt between said respective pair of said wheels,said deflection increasing an angle that form as said flat belt wrapsaround said respective wheels for providing a non-slip engagementbetween said flat belt and said respective wheels and wherein said flatbelt is reinforced with traction elements made of aramide.
 7. Drawingframe for drawing fiber sliver with drawing frame comprising a pair ofpre-drawing rollers, and a pair of main drawing rollers, each of saidrollers being fixed to a respective shaft, a wheel for driving each ofsaid shafts being fixed adjacent an end of each respective shaft, powertransmission means engaging said wheels for driving said draw framerollers, wherein at least one of said power transmission means is a flatbelt surrounding a respective pair of said wheels, a deflection pulleyengaging and deflecting said flat belt between said respective pair ofsaid wheels, said deflection increasing an angle that forms as said flatbelt wraps around said respective wheels for providing a non-slipengagement between said flat belt and said respective wheel, and saidflat belt is reinforced with traction elements made of polyamide.